I don't know if all of the themes are fully realized yet, but there are also three episodes left in which to continue to explore them. I feel like judging the themes of an ongoing work can often be difficult, since it always remains a question of how the themes will continue to be explored, and of course there's always the possibility that you're leading yourself down a different path than the creators will wind up going. (I wasn't 100% sure if my reading of From the New World was just my own politics speaking or an active thing on the part of the show for quite some time because of this) So some of this depends on how the final episodes stick the landing.
But the most important thing for me is that the themes continue to be pushed forward, and if they do that than they may will be fully realized by the end of the show. Each episode has continued to bring new layers to the established ideas, so I feel like the show is actively trying to explore these ideas.
As far as the question of who the show is for, I suppose the simplest explanation is people who want to escape from conformity. I think the show, through its blend of magical realism, lesbian overtones, and character drama, is fundamentally speaking out to anyone who has ever been targeted by other people for being different. There's a reason that this show built the climax out of one of its episodes around Kureha being tormented by her classmates and made Ginko jumping into the fire and saving the letter the big fist pump moment to end the episode on. I think the show is trying to say to anyone who has been bullied, or left out, or treated differently from others (whether that's due to being homosexual, or just having no confidence, or being disabled, or whatever) and saying "it's okay, you don't have to conform to other people's standards, you can be yourself and there will still be someone who accepts you for that". By setting it in a school, and making the teacher complicit in the whole thing, the show is also giving a pretty strong condemnation of the way in which the education system facilitates this.
At the most basic level, I feel like that's who the show is for. It uses lesbians as the most basic hook because it's Ikuhara. It's not not about lesbians, but at the same time I think if you focus too much on that as being the setup, you miss everything else that's going on around it. The relationships between the girls are our entryway into a very different story, one that's bubbling beneath the surface, initially unseen, just as the invisible storm is not something that you initially see when you look at society as a whole.
